Refer to this page that has two methods that include number of copies as arguments but it takes place when sending the report to a selected printer or deferred printing.

http://help-sage100.na.sage.com/2019/FLOR/#Object_Reference/BaseSystem/SY_ReportEngine.htm%3FTocPath%3DObject%2520Reference%7CBaseSystem%7C_____79

Although i haven't had to test number of copies, another approach is you might be able to use the GetRecordSettings and then manipulate the string returned to update the NumberOfCopies value and then use SetRecordSettings with the modified string before using ProcessReport but i don't know for sure that this will work.